1. Field of the Invention
The present invention relates to a light emitting diode, and particularly to a light emitting diode, in which a base thereof has a bottom part free from sealing and exposing outside for heat dissipation. Furthermore, the present invention also relates to a method making the light emitting diode and the blank thereof.
2. Description of Related Art
A light emitting diode has been used as an effective light source for years. The light emitting diode provides advantages such as a longer life span, a higher lightness and a lower power consumption such that it is widely applied in a signaling light, a brake light on a car, a Christmas decorative light, and etc. In addition, the light emitting diode can provides an effect of instant flash by way of circuit design as desired. Therefore, the light emitting diode is popularly used and there is a tendency for the light emitting diode to replace the conventional tungsten lamp.
As shown in FIG. 1, a typical light emitting diode provides at least two connecting pins A as a positive pole and a negative pole respectively. A base B is disposed above one of the poles at a lateral side thereof to receive a crystal chip or a dies C and a brazed wire D connects a nodal plate E extended from the other pole to constitute a circuit. The above said pins A, base B, nodal plate E are made of conductive sheet metal, and, in practice, are produced by way of integrally punch pressing a strip of conductive sheet metal.
As shown in FIG. 2, a blank used for a prior art light emitting diode is illustrated. It can be seen that the blank has been punch pressed to form a plurality of blank sections. Each blank section has connecting pins A, the base B, and the nodal plate E, and the base B has a shape of concave inward cone. The rest unnecessary parts are cut out as removals.
As shown in FIG. 3, a bent blank is illustrated. Each connecting pin A in the respective blank section is bent into an angle of 90 degrees with respect to the base B and the nodal plate E, and then the nodal plate E and the chip C can be connected with each other via a brazed wire D.
In order to assure a protection for all parts related to the circuit, each blank section are insulated by way of sealing compound. As shown in FIG. 4, a hold fixture is provided with recessions to fit with pattern frames F. Each blank section is received in each pattern frame F and fits with the pattern frame such that the base B and the nodal plate E are disposed in the pattern frame. Then, the transparent sealing compound such as epoxy resin is poured into each pattern frame F to be flush with the upper surface of the pattern frame F. When the poured sealing compound is solidified, the sealed blank sections are taken out and apart from the pattern frames F respectively. Finally, the sealed blank sections are separate into individual light emitting diodes and each of the light emitting diodes is like the one shown in FIG. 1. As shown in FIG. 1, the base B is completely covered by the sealing compound and insulated from the outside and the parts above the base B are in a state of being sealed to insulate from the outside either.
Because the light emitting diode is started instantaneously, an instantaneous current consumption is great accordingly so as to generate a higher temperature in the light emitting diode. When the light emitting diode is kept xe2x80x9conxe2x80x9d for a long period of time, the heat generated from the chip and the brazed wire is unable to be released outward and results in a phenomenon of minor flaming to affect the durability of the light emitting diode.
An object of the present invention is to provide a light emitting diode, in which the base thereof is not sealed by the sealing compound to ease the heat dissipation generated therein.
Another object of the present invention is to provide a method to make a light emitting diode, with which a bottom part of the base on the light emitting diode is free from sealing.
A further object of the present invention is to provide a blank with a plurality of blank sections used for making light emitting diodes such that a base in each blank section thereof is possible to be made free from the sealing compound.